Self-piercing stud assembly



May 30, 1939. J. J. VEILLETTE SELF-PIERCING STUD AS SEMBLY Filed A1115: 25, 1957 [/yll/A y Wwf@ ATTORNEYS In W vless than d.

structed in the manner hereinafter defined, having concentric parts telescoped one within the other with an intervening sheet of rubber I1 compressed between their respective flanges.

The stud shell is of usual construction comprising, for example, a single piece of sheet metal which has been pressed, drawn, and otherwise mechanically worked togthe shape, shown-that is, so as to have a domed head I8 with a contracted neck I9 depending from its margins, and a substantially flat radial extension Eil adapted to serve as a base flange. The latter part may, if desired, have one or more peripheral Vbeads 2i into which a part of the supporting sheet Il may be compressed, as shown inlrFi'g. `1'

In the preferred constructionth'e'lfeadl #is per-` forated as at 22 for the admission of a pointed setting tool during the attaching operation and the base flange is flared outwardly from the foot` of the neck on a curve-not a sharp breakso that-the'entranceway 23 to the stud may be slightly wider than theiinside diameter d of the contractedneck.

In one embodiment of the' invention the rivet I6 is'constructed as shown'inlFigs. 3, 4 and 5 where-it may be seen to comprise a substantially flat base flange 24 having one or more peripheral beads 25, the entire flange being generally complemental to the' flange 20.0f the'shell, and a centrally located, upstanding, "tubularl post 126. The lower-mostipart-of the post, which, for'fconvenience, willfbe` termedthe base section 21, .is ofigenerally conical proportionshaving an outside diameterd at its' foot-which is substantiallyl equal toor slightly less than, the inside diameter d ofthecontracted-'neck I9 of the shell; and an outside diameter at its top which is somewhat At the top of the baseA section, and asindicated at 28, the postis sharply contracted so that the intermediate or fup'p'er.cylindrical` section 29fhas an outside diameter which is-considerably less than the inside diameter d of the shell neck. The differencebetween these two diameters cannotl ber-prescribed: with exactness for it may vary to some extent.4 It canlbesaidphowever,1that this 'part 'of-.the post, if continued upwardly at 'the same Qdiameter, would fit loosely within the neck of the shell and leave some considerable space between the adjacent surfaces of the' parts? for the accommodation of the sheet material II (see Fig. 8). Y

` In the preferred embodiment of Figs. 3,v 4 and the upper end` of the post isimperforateand is collapsed, or flattened, so -that its then contacting vwalls form a thin flat tip 30. For convenience, this tip mayhereinafterl bereferred to as J-being axially`flat; ,orflattenedr In such case it will be understood that it has been flattened infadirection transverse to fthe longitudinal axis of the .-post. In the flattening process, as is evident, the narrow edges of'the .tip will be forced outwardly beyond the adjacent cylindrical surfaces ;of theA post .to;forma :pain of, diametrically opposite knife-like wings 3^I (Figs'.,3 and 4). The exact extent to which these wings protrude, again, cannot be-delinedffwithgprecision, `but it can be said that the width ur'of'the-completed tip, along itsflatside, should be-.substant-ially. equal to and preferably slightly `greater thanthe inside diameter d of the. cooperating neck off-the. shell; and slightly less thanthat of the entrance 23 to that neck.

'I'he dimensionsof the various parts of the studv above referred to are'all relative, that is, they are. relativeto each other, andparticularly to the inside diameter d of the cooperating shell neck I9. A better understanding thereof, and the reasons therefor, will be had from a consideration of the cooperation between the parts in a manner now to be described.

The operation wherein the stud element I5 is riveted to the supporting sheet of material I1 is illustrated particularly in Figs. 6, '7 and 8. Essentially that operation comprises the telescoping of the rivet post within the hollow head and neck of the shell, a puncturing of the inter- 'vening sheet I'I so that the post may protrude therethrough, and a rolling or upsetting of the tip of the post into the shell so as to secure the parts together and compress the surrounding portions of the sheet I'I between the cooperating flanges 20 and 24 of the separate elements.

In practice the assembling of the parts is usually carried out in an automatic machine of which only the essential die elements 32 and 33 are here illustrated. Briefly, the die 32 need be nothing more than an anvil having an upper face 34 which is complemental to the flange 24 of the rivet post, and a cylindrical central hub 35 adapted to enter the open end of the post and hold it in position. The-upper or closing die 33 has a lower face 36 which is complemental to and adapted to engage the flange 20 of the shell, a central recess 3'I capable of accommodating the domed head and contracted neck of that element, and an axially located mandrel 38 threaded into the body of the die so that the position of its pointed end 39 may be adjusted for purposes laterto be considered.

After the member and rivet have been assembled on opposite sides of the sheet of material (which is here assumed to be rubber) in the manner shown, the die 33 is brought downwardly over the shell to telescope the hollow head of that element over the tip 30 of the rivet post, and to stretch the intervening part of the sheet of material over this flattened tip. When that happens, and as may be seen in Fig. 6, the protruding wings 3I act as knives and, cooperating with the adjacent surfaces of the neck, cut a pair of slits in that part of the intervening sheet which is stretched over these wings-not, however, that part which is stretched over the extreme end of the tip, nor that which lies in the space between the flat sides of the tip and the adjacent surfaces of the stud shell as may be seen in Fig. '7. Usually at this point, or slightly later in the process,

the material lying on the thin top edge of the tip will break under its own tension thus allowing the surrounding parts to draw back along the flat sides and cylindrical parts of the postand in effect, to allow the latter to protrude through a resulting hole in the material. If it does not break in this fashion, as occasionally occurs when the supporting sheet is fairly thick rubber, it will be so weakened by the slits, and the extreme tension imposed by the telescoping and slitting actions, that the desired result will immediately follow in the manner now to be considered.

Upon continuing lthe downward movement of the die-33, the point 39 of the mandrel will enter the opening 22 in the stud head, and first contacting the material which is stretched over the tip (if not already broken as above described) will puncture the latter and permit it to draw back along the flat sides of the tip and around the cylindrical part 29 of the post. Thereafter the mandrel wlll engage the imperforate tip, and, after splitting or otherwise upsetting it, will roll it to -the lposition shown in Fig. v'-8, thus effecting substantially -a perfect 4bond between vthe parts.

The attaching operation, then, may -be summarized substantially as followsz-the tip of the rivet post, upon entering the fhollow stud neck, stretches the intervening material to some considerablefextent, Vand its wings, acting as knives against the anvil provided by the inner surfaces of thestudneck, cut a pair of slits in thestretched material which, normally, so weaken the uncut part as to cause it to break under the stress of its own tension. `Complete and positive perforation of the sheet to permit the post to 'protrude therethrough is, however, in any event assured by theaction of Ithe -pointed 5mandrelof the set-- tingltool.

'The rivet-of Fig. 3 lhaving'a closed flattened tip is usually preferred, but `the principles of the invention may -be incorporated in other ways if desired. Fig. 10,for'exampleprepresents a modified form of the invention wherein the tip 30a vis formed by Iflattening the open end of the Vcylindrical `stud post of sthe rivet i60., -in the manner shown. When'soifiattened -it will have, in effect, a thiniknife-'like uppereedga and a. -pair of wings 31a extending axially beyond `the surfaces of its cylindrical portion 29a capable of serving the functions zof fthe corresponding parts of the rivet I6 heretofore described. The manner in which this rivet is used to attach a stud shell to its supporting sheet is identical with that described in connection with the rivet of Fig. 3; and the attaching operation, too, is identical except insofar as the pointed setting tool does not, in this case, have to pierce the end of the rivet, but merely to roll, split, or otherwise upset it.

In all of the embodiments of the invention herein shown and described, the piercing of the supporting sheet is achieved by cooperation between the side edges of the rivet tip, and the side surfaces of the stud shell--not by a compression of the material between the top edge of the post and the underside of the device as has heretofore been the practice. Along this same line it may be noted that the sheet is usually fully pierced before it approaches the head of the shell, and is under such tension that when pricked by the point of the mandrel it can readily withdraw along the flat sides of the tip in the desired manner. In other words, the construction of the rivet is such as to provide not only for the slitting of the material, but also a path through which it may withdraw to a desired point. While the foregoing represents the usual result, it occasionally happens that some part of the sheet, though completely pierced, does not fully draw back around the sides as desired, but remains trapped within the shell head. Its effect upon the assembly has not, however, been found undesirable. Apparently the quantity is so small (only a very small amount can possibly be stretched over the thin upper edge of the flat tip), and the splitting or upsetting of the rivet is such that the trapped material intermingles with the mutilated part thereof, expands, and tends to form a bond between rivet and the shell.

Since certain changes may be made in the constructions without in any way departing from the true scope of the invention, it is intended that the foregoing shall be construed in a descriptive rather than a limiting sense.

What I claim is:

1. An attaching rivet or the like, of the character described, comprising a radially disposed base having a centrally located, upstanding, hollow, post-of -generally cylindrical .form terminating in a blunt tip which is flattened .in adirection transverse to the `longitudinal axis of the post with its side edges projecting radially beyond the adjacent cylindrical surface of the post at two diametricallyloppositepoints.

f2. A separable fastenerelement assembly comprising a stud shell, and an `attaching rivet telescoped one -within 'the other with a portion of sheet mate-rial `compressed between them; the stud-'shell comprising a-single piece of sheet metal having la lhollow-domedhead with a tubular contracted neck-dependingtherefrom and a substantially .fiat radial extension from the foot of the` neck serving as a base; and the rivet comprising a substantially lfiat radially disposed flange for cooperation 'with basefo'fthe shell, and a centralltubular post extending perpendicularly from the flange having an upper cylindrical part with an outside `diameter which is somewhat less than the linside diameter of the shell neck so as to leave a space `.therebetween for `the accommodation of parts of an intervening sheet of material, and va closed, axially flat, tip with a width substantially -equal to vthe inside dimension of the contracted shell lneck *so that its opposite edges .project beyond the adjacent cylindrical surfaces :of the post, r4and when telescoped in the neck, engage and tear a pair of slits in the intervening sheet of material.

3. A separable fastener element assembly comprising a stud shell and an attaching rivet telescoped one within the other with a portion of sheet material compressed between them; the stud shell comprising a single piece of sheet metal having a hollow dom-ed head with a tubular contracted neck depending therefrom and a substantially flat radial extension from the foot of theV neck serving as a base; and the rivet comprising a tubular post having a collapsed tip with a width substantially equal to the inside diameter of the neck of the shell, an immediately depending substantially cylindrical part with an outside diameter which is less than that of the inside of the shell neck so as to leave a space for the accommodation of a part of the intervening sheet, a base section flaring outwardly from the bottom of the cylindrical part so that its diameter at its foot is only slightly less than that of the shell neck, and a substantially flat flange extending radially from the foot of the base section for cooperation with the ange of the shell.

4. A self-piercing rivet for use in attaching a complemental member to an intervening supporting sheet comprising a radially disposed base flange, and a central upstanding tubular post of substantially cylindrical form having an axially fiat portion adjacent its upper end, such flat portion having thin side edges which project beyond the adjacent cylindrical surface of the post for such distance as to be capable of cooperating with inner surfaces of a cylindrical part of the complemental member when the post is telescoped therewithin, to tear an intervening sheet of supporting material so that the post may protrude through the resulting opening in such sheet.

5. A self-piercing rivet for cooperation with a hollow stud shell, comprising a substantially radially disposed base flange, and an upstanding tubular post having a blunt tip which is fiat in a direction transverse to the longitudinal axis of the post with its thin side edges projecting radially beyond the adjacent surfaces of the post for such distance that they may cooperate with the inner side surfaces of a hollow stud shell,

when the rivet post is telescoped therein, to tear an intervening sheet or material so that the post may protrude through the resulting opening i the sheet.

6. An assembly comprising a member and an attaching rivet adapted to cooperate with the member with a sheet of supporting material compressed between them; said member comprising a radial flange disposed on one side of the sheet and having a circular opening therein for the reception of a part of the rivet; and said rivet comprising a radial flange disposed on the other side of the sheet for cooperation With the flange of the member, and a tubular post extending perpendicularly from the ilange, said post having a blunt axially ilat tip with thin side edges which project beyond the adjacent surfaces of the post for such distance as to be capable of cooperating with surfaces defining the opening in the member, when the post is passed through that opening, to tear the intervening sheet material so that the post may protrude through the resulting opening in the sheet.

7. An assembly according to claim 6, further characterized in that the post of the rivet has an upper portion of substantially circular crosssection with a diameter Which is less than that of the opening in the member; in that the Width of the flat tip of the post is substantially equal to the diameter of the opening in the member.

8. A snap fastener stud assembly comprising a stud shell, and an attaching rivet having parts telescoped one within the other with a portion of sheet material disposed between them; the stud shell comprising a hollow domed head with a tubular contracted neck depending therefrom and a radial ange extending from the foot of the neck and adapted to engage one side of the supporting sheet; and the rivet'comprising a radial flange adapted to engage the other side of the sheet and to cooperate with the ange of the stud shell, and a tubular post of substantially cylindrical form extending perpendicularly from the ange, said post having an axially flattened portion adjacent its upper free end with this side edges which project beyond the adjacent cylindrical surfaces of the post, the diameter of such flattened portion being substantially equal to the inside diameter of the contracted neck of the stud whereby such Wings may cooperate with the inner side surfaces of the neck of the stud, when the post is telescoped therewith, to tear the intervening sheet material so that the post may protrude therethrough.

JEFFERY J. VEILLE'I'IE. 

